The field of the present invention relates to apparatus used in the fabrication process for semiconductor wafers, substrates, flat panel displays and other flat media, and more particularly to centrifugal processing systems with rotors adapted to receive carriers which hold wafers or other semiconductor articles or flat media, and associated transfer implements and methods for facilitating the transfer of media carriers to and from the rotor.
Wafers are typically processed in batches. For example, in manufacturing semiconductor chips, for use in computers, telephones, televisions, and other electronic products, silicon wafers will undergo many batch processing steps, such as oxidation, photolithography, diffusion, chemical vapor deposition, metallization and etching. Batch handling may occur throughout the entire production process, or for one or more processing steps or related handling operations. Batch processing of this type almost always utilizes some type of carrier or container to hold the wafers being processed.
A wafer carrier, cassette or container holds a group of wafers. The wafer carriers can be of various designs. In many applications, they are made of a suitable polymeric material, e.g., polypropylene or TEFLON® fluoropolymer. The sides and sometimes the bottom of the wafer carrier have receiving slots formed to receive and hold the wafers in a spaced array with the faces of the wafers adjacent to one another. Typically, the central axes of the wafers are aligned. The wafers are slid into the carrier or container, such as from the side or above, and are removed by sliding them outwardly. The receiving slots are shallow so that the wafer is engaged only at the peripheral edges and along a thin marginal band extending inwardly from the periphery. The term “carrier” referred to below means a carrier, a holder, a wafer boat, or a cassette.
Various of these batch processing steps during fabrication of semiconductor components involve the application of processing liquids and gases to the articles being processed. The application and removal of these processing fluids to and from the exposed surfaces of the wafers are enhanced by movement of the wafers within the processing chamber. Processing may be enhanced by centrifugal action of the semiconductor wafers which improves movement of fluids across the wafer surfaces, such as when liquids are sprayed upon the wafer and then moved across the wafer surfaces due to centrifugal forces acting upon the liquids as the wafers spin.
In one example, after semiconductor wafers have been cleaned, they must be dried because water that remains on the surface of a semiconductor wafer has at least some potential of leaving some form of residue which may interfere with subsequent operations or cause defects in the resulting products. Centrifugal action aids in the removal of water and other processing liquids so that such residues are not as likely to occur because the fluid is applied to the surface and then moves outwardly and is removed from the surfaces. Drying is also enhanced because less liquid remains on the wafer surfaces, so drying speed is increased.
In one type of prior art centrifugal processor, wafers are put into a holder or carrier in a spaced array around an axis of rotation. The carrier is lifted and loaded into a rotor. The rotor is then rotated within a processing chamber which is typically enclosed within a processing bowl or vessel. In the center of the vessel and at other peripheral locations are fluid manifolds with spray nozzles or similar outlets that are connected to a source of deionized water, heated nitrogen, or other processing chemicals, both liquids and/or gases. These or other processing fluids are thus applied to the wafers to effect washing, drying or other processing.
Certain processing tools, such as a spin rinser dryer, have been built for drying batches of wafers held in a single wafer carrier. The rotor has an opening for receiving the carrier. The carrier is loaded with wafers and loaded carrier is lifted into position and inserted into the rotor.
Thus in certain steps during the fabrication process, a carrier loaded with media needs to be inserted into the rotor of the processing chamber. There are primarily two methods used for lifting the loaded carrier and inserting it into the rotor. The first method is an operator manually lifting the loaded carrier, orienting it at the correct height position, rotational position, and tilt angle and then translating the loaded carrier into the rotor. The second method comprises a robotic arm which is programmed to automatically lift the loaded carrier, orient it at the correct height position, rotational position, and tilt angle and then translate it into the rotor.
However, robotic arm systems can be quite complicated and expensive. Particularly for processing tools built for batches of wafers held in a single media carrier, a robotic arm may not be practical. In addition, many single carrier processing machines as well as multiple carrier machines are still manually loaded by fabrication plant workers. Particularly when fully loaded with wafers, these carriers can be quite bulky and heavy. Thus there is need for improved and alternate systems for loading carriers into a processing machine.
Moreover, manually positioning a fully loaded carrier at the right height, tilt angle and rotational position can be time consuming, difficult, and involves risk of breaking wafers. Accordingly, there is a need for an improved processor loading apparatus and method.